Social interactions have been increasingly emphasized as important mechanisms influencing attitudes and behaviors including those related to reproductive health. A major motivation for this increased interest is the apparent importance of the diffusion of innovations at least in part through informal social interactions as well as from institutional sources such as family planning programs and the media. Social interactions appear to be important also for program design, sustainability, and evaluation. The project will investigate the roles of social interactions (1) in the diffusion of modern contraceptive methods and of smaller ideal family size, (2) in the diffusion of knowledge of AIDS symptoms and transmission mechanisms and the evaluation of acceptable strategies of protection against AIDS and (3) in shaping husband-wife interactions regarding family planning and more general attitudes on women's autonomy in two high-fertility and high HIV incidence sub-Saharan African countries, using longitudinal data collected or with collection already underway and extended by the project. The specific aims include: (1) To extend already existing or committed longitudinal biennial micro quantitative and qualitative data collection for women and their husbands in high-fertility and high HIV rural areas of Kenya and Malawi and to prepare the data and related documentation for public use; (2) To construct and compare indices for social interactions based on respondents' reports of the characteristics of their network partners with those based on location ("villages") with information on multiple dimensions of network partners (not only network size); and (3) to estimate multivariate relations for determinants of and impacts of social interactions to see if they are selective and to explore their impact on the three sets of reproductive health related outcomes indicated above in order to investigate the impact of wives' vs. husbands' social networks, the sensitivity of estimates to alternative representations of network characteristics and estimation methods, and some aspects of social learning as opposed to social influence.